Processing Cauliflower Variety Evaluation

A. McKeown, C. Bakker

University of Guelph

Department of Plant Agriculture

Box 587, Simcoe ON. N3Y 4N5

November, 2000

OBJECTIVES

A. 1. Evaluate cultivars for suitability for Ontario requirements, in terms of yield and various quality parameters;

B. 1. Determine for five cultivars of different maturities if cauliflower curd weight increased in the size ranges of 6 to 12" (15 - 30 cm) diameter; 2. Estimate effects of harvesting at sizes ranging from 6 to 12" (15-30 cm) on yield of cauliflower; 3. Obtain an estimate of effect of in-row spacings on yield.

MATERIALS AND METHODS

Varieties. Twenty late season cauliflower varieties were included in this year's trial. Cauliflower was seeded on June 2, 2000 into 200 cell black plastic plug trays and grown in Promix Pgx growing media from Plant Products. Plants were transplanted into the field on July 6 using a RJ mechanical transplanter. Varieties were arranged in a randomized complete block design with three replications. Plots consisted of a single 15 m long row with a row spacing of 1.0 m and 0.45 m between plants in the row. Soil was a Beverly loamy-phase with test results as follows (ppm): P = 23, K = 107, pH = 7.5. Fertilizer was applied as: preplant incorporated, 125 kg/ha N as 27.5-0-0 + 170 kg/ha P as 0-46-0 + 100 kg/ha K as 0-0-60; sidedress, 83 kg/ha N as 27.5-0-0 (July 26), 83 kg/ha N as 27.5-0-0 (Aug. 15). Weeds were controlled using a preplant incorporated application of trifluralin 0.6 kg/ha. Insects were controlled using recommended practices and applications were timed according to insect pressure. Fungicides were applied on 7-10 day intervals with the following products used: chlorothalanil 2.5L (4 sprays), iprodione 3 kg (1 spray), zineb 2.25 kg (2 spray). Plants were tied on Sept. 19, 26, Oct. 2, 11, 17, 26. The inside 10 m of each plot was harvested on Oct. 5, 11, 17, 27, Nov. 1 and graded according to industry standards. Head diameters as well as ratings on shape, colour, stem length were recorded.

Weight to diameter relationships. Five cultivars of cauliflower were transplanted at three in- row spacings of 30, 35, 45 cm. Plots consisted of two rows of each spacing and cultivar and were arranged at random within blocks. Plots were planted on July 7 and other cultural procedures were as per the cultivar trial. Three meter sections of row were assigned at random to curd size at harvest and harvested when curds were < 15 cm, 16-20 cm , 21-25 cm and 26 - 30 cm. Degree-days base 0^oC were calculated from weather data. Harvest dates (degree-days) were: Sept 22 ( 1481), Sept 27 (1543), Sept 29 (1557), Oct. 4 (1636), Oct 18 (1778), Oct 24 (1851), and Oct 31 (1918). Curds were graded with the criteria for marketability except for colour, as plants were not tied to facilitate judging of curd diameter. Each curd was weighed and the diameter taken. Regressions of weight to diameter were calculated. Yields based on grade 1, 2 and cull were estimated for each cultivar and size target for harvest. RESULTS AND DISCUSSION

Varieties. Based on average temperatures, 2000 was normal except for October which was warmer than normal. Precipitation was above normal for July, normal for August and September and dry in October. Yields ranged from good to poor in 2000. The top five yielding varieties (ranked on t/ha number one) were Solvang, Skywalker, BOS 5006, Artica and Drummond. BOS 5006 looked good , is compact and has short stems. Many varieties had a high proportion of cull curds, the primary reason was loose heads at the 9 inch target harvest size. A number of varieties also had problems with alternaria (black spot). Many heads were loose enough at the base at a small size to be culled out yet tight on top. It was very difficult to get size and quality in some varieties this year. The earlier maturing varieties were the worst. This may be a reflection on the above normal temperatures experienced at times in October. Such cultivars may need to be harvested at smaller size or at a higher frequency especially on years where looseness is a problem. Some of the earlier cultivars had a very high percent tie on the first date. White Sails, Fremont and Drummond were over 80% harvested on the first harvest. Most of the other cultivars were harvested between Oct 11 and 27. Yield index (marketable/average marketable) is a means to compare across years. Of the varieties in for three or more years, Artica had the highest average yield index. Of the standards, Fremont, Apex both were above average, although both were low in 2000.

Weight to diameter relationships of curds. Averaged over cultivars and in-row spacings, individual curd weight can be described by the following equation: -1.26+0.148*diam- 0.0008*diam². This indicates that cauliflower curd weight increases with diameter in the range tested. There is a lot of variability partially due to varieties. The response curve is consistent to that found in the literature. Plotting lines for each cultivar indicate that Apex and Artica have heavier curds at a given diameter with Fremont being the lightest. This will result in a higher yield for any given size, or, reach a yield at a smaller size. Averaged over other factors in-row spacing was not significant. Artica, Apex, had the highest number one yields as in the variety trial. Averaged over varieties and in-row spacings the yield of number one curds appears to "peak" before curds reach 25 cm in diameter. The largest size range appears to be highly prone to poor quality heads. Varieties are different in their grade distribution at given intended harvest sizes. Chieftain, Fremont and Wentworth had much higher yield of culls (essentially all) at the 30 cm target size. Chieftain, Fremont and Wentworth appear to have a tendency towards culls if let grow past 20 cm. Timing of harvest may be crucial with these varieties. These varieties may require different management programs than varieties such as Apex and Artica. There was a relationship between degree-days from transplanting and curd diameter. Degree-days from curd initiation may be useful in management of cauliflowers.